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To assess the strength of the relationships between serum carotenoids and three self-reported dietary intake instruments often used to characterize carotenoid intake in studies of diet and disease.
Participants completed a Diet History Questionnaire (DHQ), two 24 h dietary recalls (24HR), a fruit and vegetable screener and a fasting blood draw. We derived dietary intake estimates of α-carotene, β-carotene, cryptoxanthin, lutein, zeaxanthin and lycopene from each diet instrument and calculated sex-specific multivariate correlations between dietary intake estimates and their corresponding serum values.
Montgomery County, Maryland, USA.
Four hundred and seventy women and men aged 40–69 years in the National Cancer Institute's Observing Protein and Energy Nutrition (OPEN) Study.
Serum carotenoids correlated more strongly with the DHQ (r = 0·34–0·54 for women; r = 0·38–0·56 for men) than with the average of two recalls (r = 0·26–0·47 for women; r = 0·26–0·40 for men) with the exception of zeaxanthin, for which the correlations using recalls were higher. With adjustment for within-person variation, correlations between serum carotenoids and recalls were greatly improved (r = 0·38–0·83 for women; r = 0·42–0·74 for men). In most cases, correlations between serum carotenoids and the fruit and vegetable screener resembled serum–DHQ correlations.
Evidence from the study provides support for the use of the DHQ, a fruit and vegetable screener and deattenuated recalls for estimating carotenoid status in studies without serum measures, and draws attention to the importance of adjusting for intra-individual variability when using recalls to estimate carotenoid values.
To develop a method to validate an FFQ for reported intake of episodically consumed foods when the reference instrument measures short-term intake, and to apply the method in a large prospective cohort.
The FFQ was evaluated in a sub-study of cohort participants who, in addition to the questionnaire, were asked to complete two non-consecutive 24 h dietary recalls (24HR). FFQ-reported intakes of twenty-nine food groups were analysed using a two-part measurement error model that allows for non-consumption on a given day, using 24HR as a reference instrument under the assumption that 24HR is unbiased for true intake at the individual level.
The National Institutes of Health–AARP Diet and Health Study, a cohort of 567 169 participants living in the USA and aged 50–71 years at baseline in 1995.
A sub-study of the cohort consisting of 2055 participants.
Estimated correlations of true and FFQ-reported energy-adjusted intakes were 0·5 or greater for most of the twenty-nine food groups evaluated, and estimated attenuation factors (a measure of bias in estimated diet–disease associations) were 0·4 or greater for most food groups.
The proposed methodology extends the class of foods and nutrients for which an FFQ can be evaluated in studies with short-term reference instruments. Although violations of the assumption that the 24HR is unbiased could be inflating some of the observed correlations and attenuation factors, results suggest that the FFQ is suitable for testing many, but not all, diet–disease hypotheses in a cohort of this size.
We evaluated the performance of the food-frequency questionnaire (FFQ) administered to participants in the US NIH–AARP (National Institutes of Health–American Association of Retired Persons) Diet and Health Study, a cohort of 566 404 persons living in the USA and aged 50–71 years at baseline in 1995.
The 124-item FFQ was evaluated within a measurement error model using two non-consecutive 24-hour dietary recalls (24HRs) as the reference.
Participants were from six states (California, Florida, Pennsylvania, New Jersey, North Carolina and Louisiana) and two metropolitan areas (Atlanta, Georgia and Detroit, Michigan).
A subgroup of the cohort consisting of 2053 individuals.
For the 26 nutrient constituents examined, estimated correlations with true intake (not energy-adjusted) ranged from 0.22 to 0.67, and attenuation factors ranged from 0.15 to 0.49. When adjusted for reported energy intake, performance improved; estimated correlations with true intake ranged from 0.36 to 0.76, and attenuation factors ranged from 0.24 to 0.68. These results compare favourably with those from other large prospective studies. However, previous biomarker-based studies suggest that, due to correlation of errors in FFQs and self-report reference instruments such as the 24HR, the correlations and attenuation factors observed in most calibration studies, including ours, tend to overestimate FFQ performance.
The performance of the FFQ in the NIH–AARP Diet and Health Study, in conjunction with the study’s large sample size and wide range of dietary intake, is likely to allow detection of moderate (≥1.8) relative risks between many energy-adjusted nutrients and common cancers.
We describe the methods used to develop and score a 17-item ‘screener’ designed to estimate intake of fruit and vegetables, percentage energy from fat and fibre. The ability of this screener and a food-frequency questionnaire (FFQ) to measure these exposures is evaluated.
Using US national food consumption data, stepwise multiple regression was used to identify the foods to be included on the instrument; multiple regression analysis was used to develop scoring algorithms. The performance of the screener was evaluated in three different studies. Estimates of intakes measured by the screener and the FFQ were compared with true usual intake based on a measurement error model.
US adult population.
For development of instrument, n = 9323 adults. For testing of instrument, adult men and women in three studies completing multiple 24-hour dietary recalls, FFQ and screeners, n = 484, 462 and 416, respectively.
Median recalled intakes for examined exposures were generally estimated closely by the screener. In the various validation studies, the correlations between screener estimates and estimated true intake were 0.5–0.8. In general, the performances of the screener and the full FFQ were similar; estimates of attenuation were lower for screeners than for full FFQs.
When coupled with appropriate reference data, the screener approach described may yield useful estimates of intake, for both surveillance and epidemiological purposes.
To assess the epidemiological evidence on diet and cancer and make public health recommendations.
Review of published studies, concentrating on recent systematic reviews, meta-analyses and large prospective studies.
Conclusions and recommendations:
Overweight/obesity increases the risk for cancers of the oesophagus (adenocarcinoma), colorectum, breast (postmenopausal), endometrium and kidney; body weight should be maintained in the body mass index range of 18.5–25?kg/m2, and weight gain in adulthood avoided. Alcohol causes cancers of the oral cavity, pharynx, oesophagus and liver, and a small increase in the risk for breast cancer; if consumed, alcohol intake should not exceed 2?units/d. Aflatoxin in foods causes liver cancer, although its importance in the absence of hepatitis virus infections is not clear; exposure to aflatoxin in foods should be minimised. Chinese-style salted fish increases the risk for nasopharyngeal cancer, particularly if eaten during childhood, and should be eaten only in moderation. Fruits and vegetables probably reduce the risk for cancers of the oral cavity, oesophagus, stomach and colorectum, and diets should include at least 400?g/d of total fruits and vegetables. Preserved meat and red meat probably increase the risk for colorectal cancer; if eaten, consumption of these foods should be moderate. Salt preserved foods and high salt intake probably increase the risk for stomach cancer; overall consumption of salt preserved foods and salt should be moderate. Very hot drinks and foods probably increase the risk for cancers of the oral cavity, pharynx and oesophagus; drinks and foods should not be consumed when they are scalding hot. Physical activity, the main determinant of energy expenditure, reduces the risk for colorectal cancer and probably reduces the risk for breast cancer; regular physical activity should be taken.
This study sought to evaluate the benefit of utilizing a nutritionist review of a self-administered food frequency questionnaire (FFQ), to determine whether accuracy could be improved beyond that produced by the self-administered questionnaire alone.
Participants randomized into a dietary intervention trial completed both a FFQ and a 4-day food record (FR) at baseline before entry into the intervention. The FFQ was self-administered, photocopied and then reviewed by a nutritionist who used additional probes to help complete the questionnaire. Both the versions – before nutritionist review and after nutritionist review – were individually compared on specific nutrients to the FR by means, correlations and per cent agreement into quintiles.
Settings and subjects:
Three hundred and twenty-four people, a subset of participants from the Polyp Prevention Trial – a randomized controlled trial examining the effect of a low-fat, high-fibre, high fruit and vegetable dietary pattern on the recurrence of adenomatous polyps – were recruited from clinical centres at the University of Utah, University of Buffalo, Memorial Sloan Kettering Cancer Center in New York and Kaiser Permanente Medical Program in Oakland.
Reviewing the FFQ increased correlations with the FR for every nutrient, and per cent agreement into quintiles for all nutrients except calcium. Energy was underestimated in both versions of the FFQ but to a lesser degree in the version with review.
One must further evaluate whether the increases seen with nutritionist review of the FFQ will enhance our ability to predict diet–disease relationships and whether it is cost-effective when participant burden and money spent utilizing trained personnel are considered.
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